<template>
  <el-scrollbar ref="scrollContainerRef" :vertical="false" class="scroll-container" @wheel.prevent="handleScroll">
    <slot />
  </el-scrollbar>
</template>

<script setup lang="ts">
import useTagsViewStore from '@/store/modules/tagsView'
import { TagView } from 'vue-router'
const tagAndTagSpacing = ref(4);

const scrollContainerRef = ref(ElScrollbar)
const scrollWrapper = computed(() => scrollContainerRef.value.$refs.wrapRef);

onMounted(() => {
    scrollWrapper.value.addEventListener('scroll', emitScroll, true)
})
onBeforeUnmount(() => {
    scrollWrapper.value.removeEventListener('scroll', emitScroll)
})

const handleScroll = (e: WheelEvent) => {
    const eventDelta = (e as any).wheelDelta || -e.deltaY * 40
    const $scrollWrapper = scrollWrapper.value;
    $scrollWrapper.scrollLeft = $scrollWrapper.scrollLeft + eventDelta / 4
}
const emits = defineEmits(['scroll'])
const emitScroll = () => {
    emits('scroll')
}

const tagsViewStore = useTagsViewStore()
const visitedViews = computed(() => tagsViewStore.visitedViews);

const moveToTarget = (currentTag: TagView) => {
    const $container = scrollContainerRef.value.$el
    const $containerWidth = $container.offsetWidth
    const $scrollWrapper = scrollWrapper.value;

    let firstTag = null
    let lastTag = null

    // find first tag and last tag
    if (visitedViews.value.length > 0) {
        firstTag = visitedViews.value[0]
        lastTag = visitedViews.value[visitedViews.value.length - 1]
    }

    if (firstTag === currentTag) {
        $scrollWrapper.scrollLeft = 0
    } else if (lastTag === currentTag) {
        $scrollWrapper.scrollLeft = $scrollWrapper.scrollWidth - $containerWidth
    } else {
        const tagListDom: any = document.getElementsByClassName('tags-view-item');
        const currentIndex = visitedViews.value.findIndex(item => item === currentTag)
        let prevTag = null
        let nextTag = null

        for (const k in tagListDom) {
            if (k !== 'length' && Object.hasOwnProperty.call(tagListDom, k)) {
                if (tagListDom[k].dataset.path === visitedViews.value[currentIndex - 1].path) {
                    prevTag = tagListDom[k];
                }
                if (tagListDom[k].dataset.path === visitedViews.value[currentIndex + 1].path) {
                    nextTag = tagListDom[k];
                }
            }
        }

        // the tag's offsetLeft after of nextTag
        const afterNextTagOffsetLeft = nextTag.offsetLeft + nextTag.offsetWidth + tagAndTagSpacing.value

        // the tag's offsetLeft before of prevTag
        const beforePrevTagOffsetLeft = prevTag.offsetLeft - tagAndTagSpacing.value
        if (afterNextTagOffsetLeft > $scrollWrapper.scrollLeft + $containerWidth) {
            $scrollWrapper.scrollLeft = afterNextTagOffsetLeft - $containerWidth
        } else if (beforePrevTagOffsetLeft < $scrollWrapper.scrollLeft) {
            $scrollWrapper.scrollLeft = beforePrevTagOffsetLeft
        }
    }
}

defineExpose({
    moveToTarget,
})
</script>

<style lang="scss" scoped>
.scroll-container {
  white-space: nowrap;
  position: relative;
  overflow: hidden;
  width: 100%;
  :deep(.el-scrollbar__bar) {
    bottom: 0px;
  }
  :deep(.el-scrollbar__wrap) {
    height: 49px;
  }
}
</style>
